在两个节点之间画线的最佳方法

Question

我有一个简单的例子，用箭头线连接两个节点。但我怀疑这不是做这种事情的最好方法。

要求是：

1. 节点位置固定但距离可能未知。
2. 连接线应为垂直线或水平线。
3. 在两个节点的中间改变方向。

当前 MWE 如下：

\documentclass[a4paper,10pt]{article}
\usepackage{tikz}
\usetikzlibrary{arrows,positioning}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%

\tikzset{
    block/.style={draw,text width=2em,minimum height=1em,align=center},
    arrow/.style={->}
}

\begin{document}
\begin{tikzpicture}[>=stealth'] 
    \node[block] (N1) {N1};
    \node[block,below=1cm of N1,xshift=-1cm] (N2) {N2};
    \path (N1) -- (N1 |- N2) coordinate [midway] (C);
    \draw [arrow] (N2) |- (C) -| (N1);
    \path[fill=red] (C) circle (2pt); % help dot,not must have
\end{tikzpicture}
\end{document}

当前输出为：

Answer 1

您可以使用calc库来避免单独绘制路径。这就是您想要的吗？

\documentclass[border=5pt,tikz]{standalone}
\usetikzlibrary{arrows,positioning,calc}

\tikzset{
  block/.style={draw,text width=2em,minimum height=1em,align=center},
  arrow/.style={->}
}

\begin{document}
  \begin{tikzpicture}[>=stealth']
    \node[block] (N1) {N1};
    \node[block,below=1cm of N1,xshift=-1cm] (N2) {N2};
    \draw [arrow] (N2) |- ($(N1)!1/2!(N1 |- N2)$) coordinate (C) -| (N1);
  \end{tikzpicture}
\end{document}

或者你可以定义一个pic：

\documentclass[border=5pt,tikz]{standalone}
\usetikzlibrary{arrows,positioning,calc}

\tikzset{
  block/.style={draw,text width=2em,minimum height=1em,align=center},
  arrow/.style={->},
  pics/block connector/.style n args=2{
    code={
      \path [pic actions] (#1) |- ($(#2)!1/2!(#2 |- #1)$) -| (#2);
    },
  },
}

\begin{document}
  \begin{tikzpicture}[>=stealth']
    \node[block] (N1) {N1};
    \node[block, below=1cm of N1, xshift=-1cm] (N2) {N2};
    \pic [draw=green, arrow] {block connector={N2.north west}{N1.north west}};
    \pic [draw=red, arrow] {block connector={N2.south east}{N1.south east}};
    \pic [draw=blue, arrow] {block connector={N1}{N2}};
  \end{tikzpicture}
\end{document}

Answer 2

这个怎么样？

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,positioning,calc}

\tikzset{
    block/.style={draw,text width=2em,minimum height=1em,align=center},
    arrow/.style={->}
}
\newcommand\connect[2]{\path[draw,arrow] (#1) |- ($(#1)!1/2!(#2)$) -| (#2)}

\begin{document}
\begin{tikzpicture}[>=stealth']
    \node[block] (N1) {N1};
    \node[block,below=1cm of N1,xshift=-1cm] (N2) {N2};
    \connect{N1}{N2};
\end{tikzpicture}
\end{document}

结果相同：